The determination of carcinoembryonic antigen (hereinafter CEA) is well documented in the art. It is likewise well established that certain non-specific interfering substances present in the sample to be tested must be substantially removed or neutralized in some manner in order for the determination to be accurate and sensitive.
There are a number of procedures known in the art by which potentially interfering substances present in a sample of biological fluid, e.g., serum or plasma, can be removed or neutralized before testing for CEA. It is clearly an advantage to simplify the manipulations required to remove such interfering substances in a given assay in terms of time, cost, and relative ease in conducting the test.
More particularly, in the determination of CEA as taught in Freedman, et al., U.S. Pat. No. 3,663,684, a blood sample is initially treated with a glycoprotein solvent in which CEA is soluble, and the resulting solution is clarified. Examples of such solvents include perchloric acid, trichloroacetic acid, phosphotungstic acid, and the like. The purpose of treating the blood sample with the glycoprotein solvent is to remove precipitable normal proteins and interfering antigenic materials. The precipitated interfering protein material is thereafter removed from the sample by centrifugation and removal of the acid is accomplished by either dialysis or gel filtration. Both of these methods are time-consuming, expensive, and technically tedious. The number of manipulative steps also adds to the imprecision of the assay.
In accordance with the present invention, a method is disclosed for the pretreatment of a sample of human serum or plasma for assay for determination of CEA which is more rapid, easier, and less expensive than the preparative methods known in the art.